1. Field of Invention
The present invention relates, generally, to a method for recognizing at least one feature of fuel in an internal-combustion engine.
2. Description of Related Art
In some areas of the world (e.g., Brazil), for several years now, spark-ignited internal-combustion engines may be fed with different types of liquid fuel (e.g., pure petrol, hydrate alcohol, or a mixture of petrol and alcohol) that have different features (e.g., different “air/fuel” stoichiometric ratios). Recently, modern diesel engines may use fuels other than pure diesel fuel, which fuels are commercially named “bio-diesel” and consist of a mixture of diesel fuel and bio-mass-originated fuels (e.g., vegetable oils, such as rape-seed oil).
Consequently, it is important for an electronic-control unit of the engine to know the type of fuel that is actually used by the internal-combustion engine to be able to optimize combustion control as a function of features of the fuel actually used. For example, it is fundamental to know the actual stoichiometric “air/fuel” ratio to minimize generation of pollutants, and it is very useful to know volatility to guarantee correct “cold” starting of the internal-combustion engine.
Different “fuel-type recognition” methods are based on information provided by the lambda probe present in exhaust. However, there is a need in the related art to be able to use other “fuel-type recognition” methods that do not exploit information provided by the lambda probe present at the exhaust to have a possibility of recognizing the type of fuel also in “recovery” mode when the lambda probe is not working correctly. There is a need in the related art also to have a possibility of comparing the fuel-type recognition performed starting from the information provided by the lambda probe with another independent recognition to increase recognition confidence.